THE SURFACE-CHEMISTRY OF ETHYL IODIDE ON HYDROGEN-COVERED NI(100) SURFACES

The reactivity of ethyl iodides on hydrogen predosed Ni(100) surfaces has been studied by using temperature programmed desorption (TPD) spec troscopy. The data show that hydrogen coadsorption inhibits the decomp osition of ethyl groups at all coverages. Also, at ethyl iodide covera ges below saturation, the yields of both ethylene and ethane (the prod ucts of beta-hydride and reductive elimination reactions respectively) increase equally with hydrogen coadsorption, but near saturation the desorption of ethane increases at the expense of ethylene production. A small amount of ethane is also produced via the hydrogenation of che misorbed ethylene. This latter reaction occurs at higher temperature, which means that its activation energy is higher than that for the dir ect hydrogenation of the ethyl species. No coupling or H-D exchange re actions were observed in our experiments.